This application claims the benefit of a priority under 35 USC 119 to French Patent Application No. 96 12381 filed Oct. 10, 1996 and PCT/FR97/01745 filed Oct. 3, 1997, the entire contents of which are incorporated by reference.
The subject of the present invention is a system for locating cassettes for producing digital images for a radiography apparatus. In general, such radiography apparatuses comprise an X-ray emitter, a device for supporting the cassette for producing images, the organ to be radiographed being arranged between the X-ray emitter and the cassette support device, a means for processing the data thus obtained and a space for storing the cassette when it is not being used.
By way of example, there are known mammography apparatuses which comprise an X-ray source arranged on one side of the organ to be radiographed, a support table, transparent to X-rays, arranged on the other side of the organ to be radiographed, an adjustable holding plate which presses the organ onto the support table, and a housing for receiving a cassette for producing images containing an exposable film. The housing is arranged in the support table.
After an image of the organ has been produced, the cassette containing the exposed film is extracted from its housing, and the film is developed.
Such apparatuses are generally used for finding the possible symptoms of breast cancer. A first operation consists in carrying out systematic screening, which merely requires one or two frames to be taken. If these frames reveal the symptoms of cancer, more in-depth diagnosis is then carried out, which requires a larger number of frames, for example of a particular region of the organ, with a view to altering the way in which the images are represented and displayed. If the diagnosis reveals the presence of cancer, it may be necessary to perform a biopsy. A puncture system is then arranged on the radiology apparatus. The puncture system generally comprises a needle for taking a sample from a region suspected of being cancerous, for the purposes of analysis, and a needle holder. The radiology apparatus is then used for positioning the needle. The puncture system may also be used for inserting a hook equipped with a line intended for the surgeon to locate a cancerous region during an operation.
When the puncture system is used, a first frame is generally taken for centring the region to be punctured. After this, using a mechanism for tilting the X-ray source, one frame is taken at an angle of +15xc2x0 and a second frame is taken at an angle of xe2x88x9215xc2x0, with the aim of obtaining the three-dimensional co-ordinates of a point of particular interest by stereotaxis. After the needle has been inserted into the organ, at least two control frames are taken to check that the needle is in place in the region to be punctured. In practice, a total of about eight frames is reached when using the puncture system. The development of an exposable film lasts 3 to 5 minutes per frame.
Throughout the biopsy operation and the development of the frames, the organ remains perfectly immobilized relative to the radiology apparatus, and is held in compression between the table and the holding plate. The patient must therefore remain more than 30 minutes in a stationary and relatively painful position.
With the aim of reducing the time for which the organ is immobilized, the cassettes containing exposable films may be replaced by cassettes containing a means for producing digital images, capable of producing images extremely quickly. The biopsy operations are thus much shorter and reduce the discomfort of these examinations. Furthermore, cassettes for producing digital images allow the quality of the diagnosis to be improved. For economic reasons, it is desirable to use cassettes for producing digital images without changing the rest of the radiology apparatus. The cassette should be removable, so that it can be arranged either under the table, during diagnosis, or in the puncture system, during a biopsy.
A cassette for producing digital images comprises a casing, within which device for detecting the radiographic signal is arranged. This detection device may, for example, comprise a scintillator capable of converting the incident X-rays into light radiation, an optical fibre making it possible to filter most of the X-radiation which has passed through the scintillator, and protecting the components located downstream of the said optical fibre, and a charge-coupled device (CCD) array camera forming a sensitive region. In order to ensure that the cassette is positioned appropriately in the housing, the cassette is generally provided with a locking means. The cassette is also provided with an electrical cable connecting it to a data processing means, in general a microcomputer.
If the cassette is inserted into a housing in an incorrect position or without the locking means being locked, there is a risk that this will compromise the quality of the images. It may prove necessary for the microcomputer to perform different image-processing routines, using appropriate software, depending on whether the cassette is being used in the puncture system or in the housing of the support table.
The present invention is directed to a cassette location system which makes it possible to check that the cassette is positioned and locked suitably in its housing and to locate the cassette in the housing of the support table, in the puncture system or else in an inactive position.
The location system in an embodiment of the invention is intended for cassettes for producing digital images, in a radiography apparatus of the type comprising an X-ray source, a data processing means, a support for the cassette in the active position and a storage space for the cassette in the inactive position. The cassette comprises a means for detecting the insertion of the cassette into the support and a means for detecting the identification of the cassette. It is thus possible to recognize the type of cassette used as well as the position that the cassette occupies.
In one embodiment of the invention, the data processing means comprises a means for processing the digital signals output by the cassette, and a means for controlling the X-ray source.
In one embodiment of the invention, the system comprises a means for preventing the introduction of a cassette of standard parallelepipedal format into the storage space, the housing for the cassette in the storage space being provided with truncated corners, and the cassette whose introduction is allowed being of parallelepipedal format with truncated coners. This avoids conventional types of cassettes being introduced into the storage space of a radiology apparatus equipped with the location system.
Advantageously, the cassette comprises a detector for detecting insertion into the support, which is in the form of a mechanical relay.
In one embodiment of the invention, the cassette comprises a detector for identification in the storage space, which is in the form of a relay magnetically triggered by a magnet fitted to the storage space. In one embodiment of the invention, the cassette comprises a lock for immobilization in the support, a locking detector which is in the form of an electrical contact connecting to the support, and a means for digitizing the signal from the locking detector in order to send the locking data to the data processing means.
In one embodiment of the invention, the system furthermore comprises a puncture device capable of performing a biopsy and comprising a second support for the cassette in the active position. The second support may comprise a means for preventing the introduction of cassettes of standard parallelepipedal format, the housing for the cassette in the second support being provided with truncated corners, and the cassettes whose introduction is allowed being of parallelepipedal format with truncated corners. The cassette may comprise an insertion detector and an identification detector relating to the second support, which are in the form of a mechanical relay and a relay magnetically triggered by a magnet fitted to the second support.
Advantageously, the cassette comprises a lock for immobilization in the second support, a locking detector which is in the form of an electrical contact connecting to the second support, and a means for digitizing the signal from the locking detector in order to send locking data to the data processing means.
In one embodiment of the invention, the cassette is equipped with cables for transmission to the data processing means and comprises a handle intended for the cassette to be gripped and for the exit of the cable from the cassette to be protected.
By virtue of the invention, the operator immediately knows where the cassette he is looking for is located, and furthermore avoids any use of the cassette if the locking is defective or the positioning in a support is incorrect.